Rotation device for rock drills



Jan. 25, 1955 J F uc 2,700,373

ROTATION DEVICE FOR ROCK DRILLS Filed April 14, 1953 2 Sheets-Sheet 2 INVENTOR.

JACOB E. FEUCHT ATTORNEY United States Patent ROTATION DEVICE FOR ROCK DRILLS Jacob E. Feucht, Garfield Heights, Ohio, assignor, by

mesne assignments, to Westinghouse Air Brake Company, a corporation of Pennsylvania Application April 14, 1953, Serial No. 348,683

6 Claims. (Cl. 121-7) This invention relates broadly to rock drills, but more particularly to a rotation device for fluid actuated rock drills of the percussive type.

The main object of this invention is to produce a rock drill with a drill steel rotation mechanism actuated in a manner enabling free running of the rock drill piston and eliminating the tremendous friction problems heretofore encountered with rotation mechanisms of the rifle bar type.

Another object of this invention is to produce a rotation mechanism operated by the pressure fluid actuating the rock drill piston.

Another object of this invention is to design a rock drill rotation mechanism through which rotary speed of the drill still may be varied by a simple and readily effected substitution of relatively inexpensive parts.

'Another object of this invention is to provide a rock drill with a fluid actuated rotation mechanism capable of imparting torque to the drill steel far in excess of that heretofore possible in rock drills of corresponding size and capacity.

Another object of this invention is to provide a rock drill with a front end rotation mechanism having a reduced number of parts and affording a simple construction which is strong, durable and efficient.

Other objects of this invention will be apparent from the following detailed description, wherein similar characters of reference designate corresponding parts, and where- Figure 1 is a longitudinal view of a rock drill embodying the invention.

Figure 2 is a view similar to Figure l, but showing parts in different positions.

Figure 3 is an enlarged portion of Figure 1, showing details of construction, and Figure 4 is the same enlarged portion but showing the parts in their Figure 2 position.

' Figure 5 is an enlarged longitudinal sectional view taken on line 55 in Figure 1.

Figure 6' is anenlarged'cross sectional view taken on line 6--6 in Figure 2 and looking in the direction of the arrows.

'Figure 7 is an enlarged cross sectional view taken on line 77 in Figure 1 and looking in the direction of the arrows.

Referring to the drawings, 10 designates a rock drill casing formed with a piston chamber 11 having a piston 12 reciprocable therein. An automatic valve assembly 13, spacers 14 and 15 are located in the upper end of the casing, while a back head 16 forms the upper end of the rock drill. In the back head is rotatably mounted the usual throttle valve 17 which controls admission of pressure fluid into the valve assembly 13 through a port 18, annular chamber 19 and one or more ports 20.

Piston 12 has a relatively long stem 21 extending downwardly therefrom through a piston stem bearing element 22 which is mounted within the lower end of the casing 10 coaxially with the piston chamber 11. Below the bearing element 22, there is the inner end or flange 23' of a bushing 24 through which also extends the piston stem 21. This bushing is preferably pressed in a chuck sleeve 25 and is held against rotation relative thereto by any suitable means such as splines 26. has its upper end journalled in a spacer 27 fitted in the lower end of the casing 10 and the upper end of a chuck housing 28, the latter being secured to the casing 10 by the usual side bolts, not shown. The sleeve 25 is rotatably mounted in the chuck housing 28, it being held The sleeve 25 p 2,700,373 Patented J an. 25, 1955 axially therein by an annular flange 29 located between the lower end of the spacer 27 and an annular shoulder 30 formed in the chuck housing. A chuck 31 is mounted in the lower end of the sleeve 25 and is held against relative rotation by interengaging splines 32. The chuck is of conventional shape intended to fit over and engage the lugs 33 of a drill steel 34, the shank 35 of Which extends into the upper end of the sleeve 25 for receiving impacts delivered thereon by the free end of the stem 21 during the reciprocation of the piston 12. The bushing 24, sleeve 25 and chuck 31 form together a drill steel chuck member composed of sections removably secured together for ease of assembly and manufacture.

In the illustrative construction so far described, the valve assembly 13 includes an automatic valve mem ber 36 controlling rear inlet ports 37 and one or more front inlet ports 38. Reciprocation of the piston 12 is effected by pressure fluid admitted into the upper end 39 of the chamber 11 through the ports 37, thereby causing the downward stroke of the piston. As the kick port 40 is uncovered by the piston, pressure fluid is admitted on a valve shifting area, causing the valve to shift into the position shown in Figure 2 for admitting pressure fluid in the lower end 41 of the chamber 11. As the piston reaches the end of its downward or working stroke and delivers an impact on the drill steel shank 35, it also uncovers an outlet port 42 to exhaust the pressure fluid previously admitted into the upper end 39 of the chamber 11 through the ports 37. The pressure fluid admitted in the lower end 41 of the chamber 11 through the ports 38 effects the return stroke of the piston. After the piston covers the outlet port 42 and kick port 40, the air trapped between the piston and valve assembly 13 will be compressed by the piston, causing the valve member 36 to shift to the position in Figure 1 for again admitting pressure fluid into the upper end 39 of the chamber 11 and repeat the cycle. However, before the piston again starts its downward stroke, it uncovers the outlet port 42 to exhaust the pressure fluid previously admitted in the lower end 41 of the chamber 11 through the ports 38.

The construction and operation so far described depict a rock drill of the conventional type to which the improved rotation mechanism about to be described may be applied.

Referring now more particularly to the invention, the bearing element 22, while closely fitted in the casing 10, is free to reciprocate longitudinally therein, its upward movement being limited by an annular step 45 engaging a' similar shoulder 46 formed in the casing and vented through a port 47. Its downward movement is limited by engagement of its lower face with the adjacent inner end 23 of the chuck member or bushing 24. Formed on this inner end 23 of the chuck member, there are equally spaced radially extending ratchet teeth 48, each having one vertical side and one side inclined at about 45. Pivotally carried by the bearing element 22, arefour equally spaced ratchet pawls 49 which extend obliquely from the lower face thereof for end engagement with the teeth 48. Each pawl is pivotally seated in a radially extending slot 59 cut in the lower face of the element 22, the slot beingof a shape and size calculated to enable the pawl to retract entirely in the slot and become flush with lower face of the bearing element 22 when the bottom contacts the inner end 23 or teeth 48 of the chuck member. Each pawl is urged outwardly by a small spring pressed plunger 51. The number of teeth is such that when two diametrically opposed pawls are fully engaging the vertical sides of the teeth, the other two pawls are positioned about half way down the inclined sides of the teeth, thereby necessitating the chuck member to rotate an extent equal only to one-half the pitch of the teeth fortheach operative engagement of the pawls with the tee Provided in the peripheral wall of the bearing element 22, there are a plurality, preferably three, of equally spaced spiral tracks or guideways 52, inclined in the same direction as the inclined sides of the teeth 48 but to a somewhat lesser angle. Each guideway has a roller 53 fitted therein and rotatably carried by the inner end of a trunnion 54 screwed in thewall of the casing 10. A port 55 leads from the upper end 39 of the chamber 11 to an annular groove 56 surrounding the teeth 48.

With reference to the operation of the rotation mechanism, it will be understood that normally the spring pressed plungers 51 acting on the pawls 49 tend to maintain the pawls extended and consequently the bearing element 22 in its uppermost position as shown in Figures 1 and 3. As pressure fluid is admitted in the upper end 39 of the chamber 11 to effect the down stroke of the piston 12, it also flows into the annular groove 56 through the port 55, to act on the lower end of the bearing element 22 to maintain it positively in its uppermost position. In this position of the bearing element, the rollers 53 are located in the lower ends of the spiral guideways 52. As the piston 12 during its downward stroke covers the outlet port 42, the air trapped between the piston and the upper end of the bearing element 22 is compressed by the piston, thereby effecting downward movement of the element 22 upon exhaust of the pressure fluid from the lower face thereof. This exhaust takes place through the port 56 when the outlet port 42 is uncovered by the piston to exhaust the upper end 39 of the chamber 11.

During this downward movement or stroke of the bearing element 22, the rollers 53 engaging the side walls of the spiral'guideways 52 will impart partial rotation to the element, which rotation is transmitted to the bushing or chuck member 24 by at least two pawls 49 engaging the vertical sides of the teeth 48. The piston compressed air which effected the downward stroke of the element 22, will be free to exhaust when the piston uncovers the outlet port 4-2 during its return stroke. Thereafter, as pressure fluid is again admitted into the upper end 39 of the chamber 11, itwill also be supplied to the lower end of the bearing element 22 through port 55 and groove 56, thereby effecting return stroke of the element. During the return stroke, the rollers 53 engaging the side walls of the spiral guideways 52 will again impart partial rotation, in the opposite direction, to the element 22, causing the pawls 49 to ratchet over the teeth 48 preparatory to renewed operative engagement therewith.

' It is now clear that the piston stem bearing element 22 has longitudinal reciprocatory and lateral oscillatory motions imparted thereto, the former by virtue of compressed air and pressure fluid acting on the ends thereof, and the latter by virtue of the operative engagement of the roller 53 with the spiral tracks or guideways 52. It is also evident that the upper and lower ends of the element 22 constitute opposed actuating areas alternately subjected to fluid pressure for effecting the longitudinal reciprocatory motion of the element. As the downward strokes of the element are responsive to the downward strokes of the piston, the number of strokes per unit time is the same for both piston and element, and since the number of strokes of the piston is about 1500 per minute, it will be understood that the step by step rotation in one direction imparted to the chuck'member and consequently the drill steel 34, appears to be a continuous rotation. It will also be understood that the speed of this rotation can be modified by substituting the bearing element with another having spiral guideways more or less inclined, or by increasing or decreasing the travel of the bearing element.

While it is preferred to provide the spiral guideways 52, it has been found that the device will operate satisfactorily without oscillatory motion being imparted to the bearing element 22. in such instance, the guideways 52 are vertical and the function of the rollers therein is to lock the bearing element against rotation relative to the casing 10. Because the ratchet pawls 49 extend obliquely or diagonally between the adjacent end faces of the chuck member 24 and element 22, it will be understood that the distance between the pivotal end of each pawl and the teeth engaging end is gradually increased as the pawl is shifted from a diagonal to a parallel position relative to the end faces of the member 24 and element 22, thereby imparting partial rotation to the toothed member 24. in such instance, it is clear that the extent of partial rotation imparted to the chuck member for each stroke of the bear ing element is relatively small, and that the apparent continuous rotation of the drill steel is effected at relatively low rateof speed.

From the foregoing description, it is clear that the piston 12- is free to reciprocate to deliver impacts in rapid succession to the drill steel 34 without any interference from frictional load to which it is subjected with the conventional rotation mechanism of the rifle bar type.

I claim:

1. in a rock drill, the combination of a casing formed with a piston chamber, a drill steel carrying chuck memher, a drill steel striking piston and stem reciprocable in said chamber, means automatically admitting pressure fluid alternately in the ends of said chamber to effect reciprocation of said piston, a piston stem bearing element movable longitudinally in said casing to and fro relative to said chuck member, ratchet pawls pivotally carried by said element in operative engagement with ratchet teeth on the inner end of said chuck member to effect step by step rotation of said member upon movement of said element, said element having one end subjected to air compressed by said piston in said chamber to effect its movement in one direction, and means admitting pressure fluid from one end of said chamber to the other end of said element to effect its movement in the other direction.

2. in a rock drill, the combination of a casing formed with a piston chamber, a piston and stem reciprocable in said chamber, valve means automatically admitting pressure fluid alternately in the ends of said chamber to effect reciprocation of said piston, a drill steel carrying chuck member, ratchet teeth on one end of said member, a piston stem bearing element longitudinally reciprocable to and fro relative to said member, ratchet pawls pivotally carried by'said element extending obliquely from one end thereof in operative engagement with said ratchet teeth to convert the reciprocatory motion of said element into step by step rotation ofsaid member in one direction, opposed actuating areas on said element one responsive to the strokes of said piston in one direction to effect the strokes of said element inthe same direction, and the other responsive to pressure fluid admitted into one end of said chamber to effect the strokes of said element in the other direction.

3. In a rock drill, the combination of a casing formed with a piston chamber, a drill steel carrying chuck member, a drill steel impacting reciprocable piston and stem in said chamber'capable of working and return strokes therein, means automatically admitting pressure fluid alternately in the ends of said chamber to effect reciprocation of said piston, a piston stem bearing element alternately movable longitudinally in said casing forming one end 'of said chamber, ratchet pawls pivotally carried'by said element in operative engagement with ratchet teeth on the inner end of said chuck'member to effect partial rotation of said member during each stroke of said element .in one direction, said element having its end forming one end of said chamber subjected to air compressed in said chamber by said piston during its working strokes to effect the strokes of said element in said one direction, and means admitting pressure fluid from one end of said chamber to the other of said element to effect its strokes in the other direction.

4. In a rock drill, the combination of a casing formed with a piston chamber, a piston and stem reciprocable in said chamber capable of working and return strokes therein, means automatically admitting pressure fluid alternately in the ends of said chamber to effect reciprocation of said piston, a drill steel carrying chuck member, a piston stem bearing member in said casing longitudinally movable to and fro relative to said chuck member, ratchet pawls'pivotally carried by one of said members in operative engagement with ratchet teeth formed on the other member to effect partial rotation of said chuck member upon movement of said bearing member in one direction, means responsive to the working strokes of said piston to etfect movement of said bearing member in said one direction, andmeans admitting pressure fluid from one end of said chamber to one end of said bearing member to effect its movement in the other direction.

5. In a rock drill, the combination of a casing formed with a piston chamber, a drill steel carrying chuck member, a drill steel striking piston and stem reciprocable in said chamber, means automatically admitting pressure fluid alternately in the ends of said chamber to effect reciprocation of said piston, a piston stem bearing element in said casing capable of longitudinal reciprocatory and oscillatory motions, interengaging means between said casing and element responsive to the reciprocatory motion of said element for effecting its oscillatory motion, interengaging ratchet means between said member and element converting the oscillatory motion of said element into a step by step rotation of said member in one di rection, opposed actuating areas on said element one exposed to air compressed by said piston in said chamber to effect longitudinal movement of said element in one direction, and means admitting pressure fluid from one end of said chamber on the other actuating area to effect longitudinal movement of said element in the other direction.

6. In a rock drill, the combination of a casing formed with a piston chamber, a drill steel carrying chuck member, a piston and stem longitudinally reciprocable in said chamber, means automatically admitting pressure fluid alternately in the ends of said chamber to eifect reciprocation of said piston, a piston stem bearing element in said casing capable of longitudinal reciprocatory and oscillatory motions, interengaging spiral track and roller means between said casing and element responsive to the reciprocatory motion of said element to effect its oscillatory motion, ratchet pawls pivotally carried by said element in operative engagement with ratchet teeth on the inner end of said chuck member to convert the oscillatory motions of said element into a step by step rotation of said member in one direction, means responsive to the longitudinal movement of said piston in one direction to effect longitudinal movement of said element in the same direction, and means admitting pressure fluid from one end of said chamber to one end of said element to effect its longitudinal movement in the other direction.

Oldham Sept. 22, 1903 Chapman June 4, 1929 

